The present invention relates to a maintenance device for an ink-jet head which ejects droplets of ink. More particularly, the invention relates to a maintenance device for an ink-jet head having a plurality of ink droplet-ejecting portions, an ink-jet recording device having a maintenance device, and an ink-jet head maintenance method.
One method for recording images on a recording medium involves using an ink-jet head having ink droplet-ejecting orifices and causing ink droplets to be ejected from the orifices in accordance with image signals.
In an ink-jet head which ejects ink droplets from such orifices, ink droplets adhere to the surface of a nozzle plate (also referred to herein as a “head substrate”) on which nozzles (more specifically, nozzles with openings that serve as ink droplet-ejecting orifices) are formed.
When such ink droplets adhere to the nozzle plate, particularly in the vicinity of the orifices, the direction in which the ink is ejected becomes unstable, making it impossible to form a high-quality image.
Methods for removing ink droplets and debris adhering to the surface of the nozzle plate include, for example, rubbing the surface with a flat blade formed of a soft material so as to dislodge the ink droplets and debris, and bringing an ink droplet and debris-absorbing member into contact with the nozzle plate so as to absorb the ink droplets and debris.
However, if a low-hardness material is used in the nozzle plate so as to enhance the nozzle orifice machining precision during ink-jet head production or if the surface of the nozzle plate has been given a liquid-repelling treatment, the above methods which entail physical contact using a blade or absorbing material may damage the edge structure of the nozzle or mar the liquid repellent-treated surface.
Damage to the nozzle edge structure or marring of the treated surface disrupts the ejection of the ink droplets, making it impossible to form a high-quality image.
Devices for removing ink droplets adhering to the surface of the nozzle plate include the maintenance devices described in JP 05-201028 A and JP 08-58103 A.
JP 05-201028 A discloses a maintenance device for an ink-jet head having a plurality of nozzles formed in an array within a head main body and having a head main body end which is formed as a flat surface. The maintenance device includes a negative pressure-generating means for generating a negative pressure which is lower than atmospheric pressure, a local suction means which is connected to and communicates with the negative pressure generating means and has formed therein a suction port of a size that faces one or a plurality of unit nozzle regions, and a suction port displacing means for relative displacement of the suction port on the local suction means in the direction in which the nozzles are arrayed.
JP 08-58103 A discloses an ink-jet device in which, when ink or the like adheres to the nozzle plate and maintenance is required, a cap is moved and positioned so as to be separated from the nozzle plate by a specific distance L between a cap rubber and a nozzle plate face at the front surface of the head, and a pump is operated in this state, thereby aspirating ink on the nozzle plate face into the cap.
This ink-jet device is described as being capable of removing ink without deterioration of the water-repellent film on the nozzle plate.
As described in JP 05-201028 A and JP 08-58103 A, damage to the surface of the nozzle plate during maintenance can be prevented by the use of suction at a position separated from the nozzle plate by a fixed distance.